1. Field of the Invention
The present invention relates to a device for preventing fluid free flow in a fluid administration system, and more particularly to an anti-free flow valve device disposed within a lumen of a tube assembly. More specifically, the present invention relates to an anti-free flow valve device that prevents fluid free flow when the tube assembly is in a relaxed condition, while permitting fluid flow when the tube assembly is in a stretched condition.
2. Prior Art
Administering fluid, such as medication, saline and nutritional formula, to a patient is generally well-known in the art. Typically, fluid is supplied to a patient by a tube assembly of a fluid administration system which provides a fluid pathway between a fluid source and the patient. The fluid is supplied to the patient through the tube assembly by either an enteral connection which accesses a visceral organ (gastrointestinal feeding) of a patient or through a parenteral connection which accesses a non-visceral organ (intravenous feeding).
Fluid flow rate through the tube assembly may be manually controlled by a mechanical clip which is designed to progressively occlude the tube assembly and selectively impede fluid flow induced by gravity. One such mechanical clip which operates to occlude a portion of the tube assembly is a conventional roller clamp that has a hollow body with opposed openings and a pair of angled slots formed opposite of one another transverse to the openings. The clip further includes a wheel having an axle which is coupled to the body through the slots. A portion of the tube assembly is then inserted through both the openings of the roller clamp and the wheel axially advanced along the slots to pinch a portion of the tube assembly against the body which progressively occludes the tube assembly. Although the mechanical clip operates to provide a cost-efficient method for controlling fluid flow rate, the clip must be manually actuated by the user. Further, the wheel of the mechanical clip can be inadvertently bumped or jostled out of position resulting in an inappropriate flow rate.
In order to better enhance fluid flow rate control in a fluid administration system, calibrated pumps have been utilized. One such calibrated pump is a peristaltic pump connected in-line along a portion of the tube assembly between the fluid source and the patient. The peristaltic pump advances the fluid through the tube assembly by progressively occluding successive portions of the tube assembly and urging each occluded portion forward by rotating the rotor of the pump. When a peristaltic pump is utilized to control the fluid flow rate, mechanical clips are typically not employed or are disengaged to prevent the clip from interfering with the operation of the pump.
Although peristaltic pumps have substantially advanced the art, further improvements are required. For example, once the tube assembly is disengaged from the rotor of the pump fluid flow rate through the tube assembly becomes unrestrained as fluid is drawn through the tube assembly by the force of gravity. This situation is known as fluid free flow and may present an undesirable, or even life-threatening situation, if left undetected because of the risk of overfeeding or overmedicating a patient.
In order to overcome the above-noted drawbacks to fluid administration systems utilizing pumps, several devices have been suggested which operate to automatically occlude a portion of the tube assembly and prevent fluid free flow when the tube assembly becomes disengaged from the rotor of the pump while also permitting uninhibited fluid flow when the tube assembly is properly engaged to the pump. For instance, a variety of automatic occluders have been suggested to improve the art such as those disclosed in U.S. Pat. No. 4,689,043 to Bisha entitled xe2x80x9cIV Tube Activatorxe2x80x9d which describes a clamp for use with a peristaltic pump. The clamp includes a V-shaped channel which is spring biased into a closed position where the narrow portion of the V-shaped channel is sized to substantially crimp, or occlude, a portion of the tube assembly and prevent fluid free flow therethrough. The clamp is placed in an open position by a handle which overlays the pump and depresses the springs such that the tube assembly is positioned within the wider portion of the V-shaped channel to permit unrestricted fluid flow through the tube assembly when the pump is operating. When the handle is released, the V-shaped portion will automatically slide into the closed position and prevent fluid free flow by occluding a portion of the tube assembly.
Another automatic occluder is disclosed in U.S. Pat. No. 5,704,582 to Winterer, et al. entitled xe2x80x9cPinched Clipped Occluder for Infusion Setsxe2x80x9d which describes a clip that is positioned between a housing and a cover of a pump. The clip has a plunger biased by a spring against the lumen of the tube assembly so that the lumen becomes occluded by the plunger. Fluid flow through the tube assembly may only be established when the plunger is biased away from the lumen of the tube assembly which occurs when the cover is properly coupled with the housing. However, once the cover becomes disengaged from the housing, the plunger is automatically biased into the closed position by the spring to prevent fluid free flow.
Although both of the aforementioned automatic occluders have advanced the art, both devices are mechanically complex and prone to mechanical failure. In addition, the mechanical complexity of these devices also results in occluders which are expensive to manufacture. Accordingly, there is a need in the art for a valve device disposed within a lumen of a tube assembly that is capable of preventing fluid free flow when the tube assembly is disengaged from the pump, while also being mechanically uncomplicated, reliable and low cost to manufacture.
In brief summary, the present invention overcomes and substantially alleviates the deficiencies present in the art by providing a valve device for a fluid administration system which is adapted to prevent fluid free flow when the tube assembly is in a relaxed condition, while permitting fluid flow when the tube assembly is engaged to the pump.
Preferably, the pump of the fluid administration system used with the present invention includes a rotor for advancing fluid through the tube assembly and a pair of recesses formed adjacent the rotor for retaining portions of the tube assembly to the housing of the pump during operation of the system. The tube assembly is an elongated tube with a lumen formed therethrough which provides a fluid pathway having three interconnected tube segments each including respective distal and proximal ends. The distal end of the first tube segment is attached to the fluid source, while the proximal end thereof is connected to the distal end of the second tube segment by a drip chamber having an abutment surface. The proximal end of the second tube segment is interconnected to the distal end of the third tube segment by a coupling having an external flange. Finally, the proximal end of the third tube segment is connected to an enteral or parental connection on the patient.
The tube assembly is engaged to the pump by engaging the second tube segment around the rotor with the abutment surface and external flange engaged within the respective recesses of the pump. Preferably, the length of the second tube segment permits the abutment surface and the external flange of the tube assembly to be properly captured by the first and second recesses, respectively, and place the second tube segment in a stretched condition around the rotor of the pump.
Preferably, the valve device comprises a body disposed in a flexible tube portion that forms a part of the valve device and is interposed between and in communication with the second tube segment and the coupling. The preferred embodiment of the body includes a sealing member formed at the distal end thereof with a plurality of legs which extend in a tapered fashion from the plunger portion and collectively terminate at an annular flange or retention member that defines an opening at the proximal end of the body. An aperture is formed between each of the legs and communicates with the opening through an inner chamber formed between the legs of the body. The tube portion is made of a flexible elastomeric material which securely houses the body inside a channel defined by the valve tube portion having proximal and distal ends. The proximal end of the channel defines a groove and the distal end forms a valve seat or outlet. The groove is formed around the wall of the channel and is sized and shaped to securely retain the retention member of the valve body within the channel. The valve seat functions as part of a sealing arrangement which is adapted to provide a fluid tight engagement with the sealing member of the body when the valve device is placed in the closed position. When the valve device is in the closed position, the head of the sealing member is securely seated against the valve seat and prevents fluid flow therethrough.
In an alternative embodiment of the body, the legs of the body extend from the sealing member in a straight fashion rather than being tapered as disclosed in the preferred embodiment. In yet another alternative embodiment, the body includes a tapered elongated shaft which extends from the sealing member and terminates at a proximal portion having opposing dual channels formed therethrough which communicate with the either side of the elongated shaft. The proximal portions of both embodiments are also configured to retain the body within the groove formed around the valve tube portion.
In operation, the valve device of the present invention prevents fluid free flow whenever the tube assembly is disengaged from the pump while also permitting fluid flow when the tube assembly is engaged around the rotor of the pump or manually actuated by the user. The body is inserted within the channel of the tube portion during manufacturing of the valve device. To utilize the valve device of the present invention with the fluid administration set, the user first connects one end of the tube assembly with a fluid source and allows fluid to travel through the tube assembly until it reaches the point where the valve device is disposed. The user then primes the tube assembly to evacuate air from all the remaining portions of the tube assembly. Preferably, the tube assembly may be manually primed by pulling or stretching the portion of the tube assembly adjacent the tube portion which pulls the body away from the coupling and unseats the sealing member from the valve seat. This operation allows fluid to flow and forces air out the remaining portions of the tube assembly until all the air is evacuated from the tube assembly. Once fluid administration system has been primed, the proximal end of the third segment may be attached to either an enternal or parenternal connection made with the patient.
To regulate and urge fluid through the tube assembly, the tube assembly is engaged around the rotor of the pump. To properly engage the tube assembly, the abutment surface of the drip chamber is inserted within the first recess of the pump, while the second tube segment is stretched by the user around the rotor. The external flange of the tube assembly is then inserted into the second recess in order to retain the second tube segment in a stretched condition around the rotor. In the stretched condition, a tensile force is applied along the second tube segment which also stretches the tube portion and places the valve device in an open position. In the open position, the body is pulled away from the valve seat which unseats the sealing member from the valve seat and permits fluid flow through the valve device. However, if the tube assembly becomes disengaged from the pump, either intentionally or unintentionally, the tensile force applied along the second tube segment and the tube portion is released which places the valve device in the closed position. In the closed position the sealing member of the body is driven back against the valve seat in fluid tight engagement as the second tube segment and the tube portion move from the stretched condition to the relaxed condition and fluid free flow is prevented through the valve device. Because the retention member of the valve body is always retained within the groove of the tube portion, the body is placed in the open position whenever the second tube segment and the valve tube portion are in the stretched condition. Conversely, the body is always placed in the closed position whenever the second tube segment and the tube portion are returned to the relaxed condition.
Accordingly, the primary object of the present invention is to provide a valve device which prevents fluid free flow in a fluid administration system.
A further object of the present invention is to provide a valve device that prevents fluid free flow whenever the tube assembly is disengaged from the pump, while permitting fluid flow whenever the tube assembly is engaged to the pump.
Another object of the present invention is to provide a valve device which prevents fluid free flow while being mechanically simple in order to reduce the opportunity of mechanical failure.
Another further object of the present invention is to provide a valve device of the above character that forms a part of the tube assembly.
These and other objects of the present invention are realized in the preferred embodiment, described by way of example and not by way of limitation, which provides for a valve device for use in a fluid administration system to prevent fluid free flow within the tube assembly whenever the tube assembly is disengaged from the pump.
Additional objects, advantages and novel features of the invention will be set forth in the description which follows, and will become apparent to those skilled in the art upon examination of the following more detailed description and drawings in which like elements of the invention are similarly numbered throughout.